Fiber optics are commonly used for many applications, including data transfer applications and a number of optical computing applications. For data transfer, light is typically transferred down a length of optical fiber from a source to a destination. The optical fiber comprises a light guide that operates according to principles of total internal reflection (TIR). The light may be modulated as it is introduced into the optical fiber in order to encode information in the transmitted light. For example, information may be encoded in the light by switching the light on and off, modulating the light intensity, modulating the frequency and wavelength of the light, or various combinations. In some cases, a plurality of different frequencies of light can be multiplexed on a given light guide for simultaneous transmission.
Optical computing is viewed as a potentially high-speed alternative to conventional computing techniques. The goal of an entirely optical computing machine is to replace the electrical currents and voltages common in conventional computing techniques with manipulations of light. Current implementations typically rely, at least in part, on opto-electronic elements wherein electrical signals may be converted to optical signals, transferred or manipulated, and then converted back to electrical signals. However, purely optical computing aims to virtually eliminate the opto-electronic components altogether, and therefore, eliminate the need for conversions from optical to electrical signals. Light controlled gates, light to light transistors, light amplification devices, and a number of other optical computing components are currently being developed to realize practical optical computing applications.
One type of optical component that may be very useful for optical computing, data transfer applications, or other optics applications is an optical delay line. An optical delay line is generally a relatively long length of optical fiber that introduces a time delay to an optical signal. The amount of time required for light to traverse the optical fiber (at the speed of light through the medium) is referred to as the optical delay. Delay lines have many applications, including applications as short-term transient memory elements, timing elements, or phase delayed comparator devices. In some cases, micron adjustments to the length of an optical delay line may equate to changes in the optical delay on the order of pico-seconds, which make optical delay lines attractive as accurate timing elements.
Optical fiber, such as that used for optical delay lines, is typically drawn or extruded and then wrapped around a large spool. In some cases, the optical fiber may be drawn and then embedded in a resin to form a more rigid and robust optical part. Features may also be added to optical fibers, such as diffraction gratings, to facilitate manipulation of the light that traverses the fiber.